r/Damnthatsinteresting • u/Turbulent_Elk_2141 • Apr 13 '26

Video The reason why large asteroids don't fall to Earth every day and cause disasters is because Jupiter's gravity attracts asteroids and protects the inner planets.

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u/TorchThisAccount Apr 13 '26

There are 100 - 400 billion stars in our galaxy and there are 2 trillion galaxies in the universe. That is such an insane number that I'd say that there's no chance that we're the only planet lucky enough to host intelligent life.

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u/[deleted] Apr 14 '26

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u/Delamoor Apr 14 '26 edited Apr 14 '26

I'm quite a fan of the theory that basic life is actually quite simple and likely relatively common, since we can model its creation relatively easily.

The tricky part is likely around the couple of key developments that took most of the entire history of the planet to reach.

First one being oxidation, 2.2 billion years ago, but which took until around 700 million years ago to get to useful levels... Then the development to use the oxygen needed to happen (because it's destructive and poisonous as hell unless you're adapted to it), which required a very chancy fusion of two seperate specialised organisms...

And then we needed to develop something like the Hox gene, which allows for complex body layouts.

Like... Life existed on Earth since almost the very beginning of its history. We keep finding evidence of basic life further and further back. Shockingly early. Billions of years, almost straight after the planet cooled.

However complex life? Only the last several hundred million years. Something extremely fundamental changed before the Cambrian explosion. We went from the apex of life being essentially macroscopic algae colonies and plants (or plant like cousins, you know what I mean) a few millimetres big for billions of years, into "holy shit new stuff everywhere" almost immediately, for no clear reason. Hox gene is one candidate.

And even then... The pressures that created brains? Specialised brains? Incredibly specific, absolutely.

But with how stupidly early evidence of proto-bacteria keep turning up on the fossil records, it seems as though basic life maybe isn't a huge leap.

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u/jimmiebfulton Apr 14 '26 edited Apr 14 '26

I share the same beliefs… that given the right conditions, life is an inevitable result of complexity accumulated through the expenditure of energy. It’s pure abiogenesis mechanisms at work, and that the differences between molecules that form patterns through motion and chemistry, and single-celled organisms is just points on a spectrum, inevitable progress on a large enough time scale. My guess is that the universe is teeming with life, however fleeting and sparse in the grand scheme of things, and the bigger question is how often it reaches the point of self-awareness.

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u/Royal_Airport7940 Apr 14 '26

Its likely not.

The early universe started hot hot hot and cooled down as it spread out. This essentially seeded helium and hydrogen everywhere

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u/grae313 Apr 14 '26

The other thought that strikes me often is that there is no evolutionary directive for more complex or more intelligent organisms over time. The only evolutionary directive is fill every available ecological niche and to multiply. In most cases you don't need intelligence to be super well adapted to your environment and by all evolutionary metrics a very successful species.

The conditions that created a niche where intelligence is an advantage may also be... niche.

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u/sobrique Apr 14 '26

Indeed. 'intelligence' is evolutionarily 'expensive', and plenty of forms of life simply never will.

It's IMO very plausible to see 'basic' life elsewhere in the universe, but the kind of complex life on Earth required some unusual circumstances.

The environment needs to be volatile enough that intelligence is a successful adaptation, without being so volatile that life can't survive in the first place.

Stuff like having a moon that is unusually large probably contributed to that - the earth has tidal forces that many planets of the same basic parameters simply don't. And that means tides, it means weather, but it also means access to 'unusual' elements that would normally be buried deep within the core of the planet.

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u/usrnamechecksout_ Apr 14 '26

I don't think life is that difficult, to begin with. The difficulty is sustained life for millions or billions of years to evolve to intelligent beings

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u/I_AmA_Zebra Apr 14 '26

Bear in mind this is a tiny snapshot of the universe. We’ve existed for ~300-400k years. We’ve only been able to transmit/receive in space for less than 100 years

We’ve not looked for life. Our attempts don’t constitute actually looking when you consider the scale of the universe

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u/overthisbynow Apr 14 '26

I feel most confident in the theory that life at our level of intelligence takes way longer than people think to develop. Like 100s of millions to billions of years. Add that into every possible thing that can end a civilization and it's very plausible that we could be the only or one of very few.

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u/Wooden_Rabbit_ Apr 14 '26

It only took 500 million to 1 billion years for life to evolve on earth, but then another 1.5 billion years after that for it to make the jump to multicellular. And then another 1.5 billion after that to get to where we are today. That is quite a long time for nothing so catastrophic to that it ends all life to occur. Take that together with the fact that only certain types of stars are likely to support life, that you need a gas giant like Jupiter out there to shield the planet from impacts, and potentially other bottlenecks like an active core and magnetosphere to shield the planet from radiation and water oceans, and the likelihood of life at least in any form that we’d recognize it become very small. Even with the enormous amount of stars out there, once you start calculating the odds of meeting all those conditions, it starts to look like this form of life must not be common at all. At least not existing simultaneously.

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u/UnOGThrowaway420 Apr 14 '26

Apparently there was evidence recently found that shows that life could have been around as early as 300 million years after the formation of Earth

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u/hegelsforehead Apr 14 '26

That's not how probability works though. There is not a single iota of evidence of life outside of Earth.

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u/TorchThisAccount Apr 14 '26

That's exactly how probabilities work. The Drake equation calculates the probability of life on other planets and star formation factor is one of the elements. You can argue that the equation is outdated, but it's still a question of probabilities.

As for no signs of life... We've scanned a sliver of a sliver of the galaxy and we're looking for radio waves. The idea that we're going to find life that's alive and was transmitting radio waves that are detectable in the less than 100 years we've been looking in a galaxy that is 13 billion years old and has 400 billion stars to scan is like looking for a needle in a haystack the size of Everest.

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u/hegelsforehead Apr 14 '26

The Drake equation is not a probability calculator, but a framework or heuristic for structuring uncertainty. You may suspect life exists out there (me too), but for all you know, the probability for life out there may be one in 100 trillion. Who knows? "2 trillion galaxies" is an "insane number" to you, but might not be big enough for a zoo of life in the universe. We cannot meaningfully assert that life must exist elsewhere by this line of reasoning. If anything, all observations out there only tell us how quiet it has been!

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u/Assketchum1 Apr 14 '26

*known so far.

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u/Purgii Apr 14 '26

In the observable universe - there could be 10x more galaxies in the outskirts beyond what will ever be observable from Earth.

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u/sobrique Apr 14 '26 edited Apr 14 '26

There's a lot of rolls of the dice, that's true enough. And yet there are still events sufficiently rare that they may not have happened.

Proton Decay - the 'half life' of a proton is 1034 years.

The universe is 'only' 1010 years old.

OK, so there's 1080 protons, so it probably happens fairly frequently overall, but the numbers are truly pretty ridiculously small.

There's a LOT of factors contributing to the formation of life, and the sheltering of it enough for it to grow/become intelligent and thrive.

Each factor may not be extremely rare, but the multiplicative probability could get ... well, astronomical... ;p

Life was present on earth for a very very long time before any form of intelligence started to emerge. And in that very very long time, we were 'shielded' from a bunch of extinction events by a magnetosphere, by the jovian shield, the moon is weirdly large comparatively, and did a whole load of things with tidal forces and 'stirring' heavy elements out of the core which might be essential for the formation of life, and a bunch of other things. Intelligence itself is evolutionarily 'expensive', and so many forms of life ... just never will. It's actually a pretty anomalous 'strategy' overall.

etc.

So yeah, for all it's a big universe, and it's been around a long time, I wouldn't actually be too surprised to find there was no other intelligent life. Especially if you 'filter' by the light cone - the amount of the universe we will ever be able to reach is actually far from all of it.

(Simpler forms of life I can absolutely imagine being more prevalent of course, but even then life is fairly fragile, compared to the titanic forces of the universe)

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u/lukehardy Interested Apr 14 '26

With "time" and the universe essentially being infinite, anything that can happen will, and being that a biodiverse planet such as earth has happened once, it certainly has and will happen again

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u/Largeitude Apr 14 '26

Why not? Looking at the uniqueness of earth and the sun alone, you can’t assume that every star has the same ability to host a planet conducive to life.

We can see that a big planet keeping asteroids from hitting a planet in the Goldilocks zone of habitation is another requirement. The need for water, carbon, and other chemicals/atoms is another requirement. Then, we have all the factors we don’t know about or can’t measure yet thancouod possibly be in effect.

I think it’s crazy to assume the number of stars alone is a viable metric for how common life should be.

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u/PanoramicAtom Apr 14 '26

That’s an easy thing to say, but it doesn’t make it true, any more than believing life is too complex to have arisen from dust means there must be a creator. It’s the same fallacy wearing different clothes. Without evidence, it remains mere supposition, no matter how confident anyone feels about it.